<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #ldh {
            color: red;
        }
        
        img {
            width: 200px;
            height: 200px;
        }
    </style>
</head>

<body>
    <button id="ldh">刘德华</button>
    <button id="zxy">张学友</button><br>
    <img src="images/ldh.jpg" alt="" title="刘德华">
    <script>
        var ldh = document.getElementById("ldh");
        var zxy = document.getElementById("zxy");
        var img = document.querySelector("img");
        zxy.onclick = function() {
            img.src = "images/zxy.jpg";
            img.title = "张学友";
        }
        ldh.onclick = function() {
            img.src = "images/ldh.jpg";
        }
    </script>
</body>

</html>